I go out in public all the time, and I am unmistakably a man. I would still be unmistakably a man no matter what I did to disguise it. And it is not a crime for people to notice.
How about somebody in a burka?
What about them?
If you are asking "could I tell the difference between a man in a burka and a woman in a burka just by casually interacting with them", the answer is "probably". But if it's not "probably", I'd probably just use 'they' to refer to them, indicating I was not certain of their sex.
Have you ever spoken to adult human beings? Have you ever noticed that you can usually tell somebody's sex from their voice alone? Or that men and women have different gaits and different heights and different faces and different body fat distributions and different hips and different chests?
Has all of this escaped your notice your entire life?
And there used to be a pretty hilarious drag queen show here in town we saw once. You wouldn't realize everyone on stage was actually male.
So, Jarhyn's objection to my correctly observing somebody's sex is that I am 'outing' them or 'doxxing' them, or some other insane-o-sphere delusion that I am revealing information about their genitals that is private.
You, and Jarhyn it seems, appear to believe that most people most of the time can't tell the sex of somebody by merely looking at them. That is such an absurd thing to believe I can't even.